1. Field of the Invention
Exemplary aspects of the present invention relate to a manually operated walk-in system of a powered vehicle seat.
2. Description of the Related Art
Seats of a vehicle such as an automobile may be provided with a reclining mechanism that allows the seat back to pivot at a base portion thereof. These seats may also be provided with a sliding mechanism that allows the seat to travel in the fore-aft direction of the vehicle. Both the reclining mechanism and the sliding mechanism may be operated using individual manual levers, typically located on the vehicle seat. Also the reclining mechanism and the sliding mechanism may be replaced by a powered actuator that performs the sliding and reclining functions without additional effort from the user. Seats equipped with these features are typically called power seats or power assisted seats.
Seats may also include a walk-in feature that assists the egress and ingress of the vehicle. Typically, the walk-in feature allows one to more easily enter a space behind the seat by moving the seat forward and by rotating the seatback forward. Therefore, the walk-in feature has a recliner function and/or a slide function. These walk-in functions can be powered or manually actuated.
When the walk-in function is not in use, the sliding mechanism is locked in order to prevent the seat from traveling in the fore-aft direction of the vehicle. The sliding mechanism is locked by the connection between a lock lever fixed to the vehicle and a lead screw nut fixed to the seat. In some designs, interdigitated teeth are used to connect the lock lever to the lead screw. In the interdigitated teeth designs, recesses in the lead screw nut correspond to raised teeth from the lock lever, whereby the teeth of the lock lever occupy the recesses in the lead screw nut and prevent motion in the fore-aft direction. If the teeth are retracted from the recesses in the lead screw nut, then motion in the fore-aft direction is allowed. U.S. Pat. No. 5,516,071 illustrates a conventional walk-in mechanism.
One challenge with the interdigitated teeth design is that during a crash, extreme force on the teeth may cause the teeth bend resulting in the failure of the lock and the seat sliding the fore-aft direction. A second challenge is that the interdigitated teeth design occupies significant space due to the way in which the lock lever teeth are retracted from the recesses in the lead screw nut.